Jellyfish are the simplest moving animals on our planet. They are closely related to corals and anemones and appear in the fossil record at about 600 million years ago. Jellyfish do not have a brain, heart, nervous system, internal organs or anything else. Jellyfish have a few simple parts; tentacles for capturing food, a swimming/pulsing bell for movement, oral arms for capturing and concentrating food, sensor spots along the margin of the bell (these sense light and gravity) to aid movement, a gut for digestion and gonads for reproduction. Some jellyfish are a little more advanced than others and actually have eyes like box jellies. Some jellyfish are a lot simpler than others like the moon jellyfish! Jellyfish come in almost every shape and color imaginable, some are upside down and some even produce their own light!